1. Field of the Invention
The present invention relates to a method of preparing a nanowire grid polarizer and a nanowire grid polarizer prepared using the method, and more particularly, to a nanowire grid polarizer which has a stable structure obtained using a mesoporous material and a nanowire grid polarizer prepared using the method.
2. Description of the Related Art
Recently, a demand for display devices having high resolution, high efficiency, and low power consumption has been increasing, so as to display a large capacity of image information, such as a natural moving image. Also, a demand for large display devices is increasing and thus highly productive large-area processing techniques to produce components suitable for such large display devices are required. Specifically, liquid crystal displays (LCDs) provide only 5-7% of light emitted from a light source, such as an LED or a CCFL, to a user and have very low light efficiency, and thus, there is a need to improve such low light efficiency that may be caused by many problems such as the fact that the LCDs are operated by an LC switch and only one polarized light out of an incident beam can be used, which is well known to one skilled in the art. In a conventional LCD device, a liquid crystal and two absorption-type polarized films are used to perform optical switching. In such structure, however, arithmetically about 50% of a non-polarized incident beam is not used (before and after passage through the liquid crystal). To reduce such light loss, 3M Co. developed a dual brightness enhancement film (DBEF) having high efficiency to improve brightness. However, the DBEF is not a complete polarized device, and is expensive because the DBEF requires about a 600 or more-layer deposition process.
Also, the absorptive polarizers can be replaced with reflective polarizers, such as a wire grid polarizer (WGP), which transmit light having a predetermined polarized direction but reflect light having another polarized direction and reuse the reflected light.
A WGP must have a metallic lattice structure in which the metal wires are separated by half or less of a minimum wavelength of a wavelength range of an incident beam. A WGP having such small line width is produced, in general, by forming a nano lattice pattern using an e-beam or laser interference exposure and forming a mold using a polymer material corresponding to the formed nano lattice pattern. Specifically, the mold can be formed using a nano imprinting method, such as a UV calcination method or a hot embossing method. The obtained mold is then subjected to an oblique deposition process, such as a lift-off process or CVD process of a semiconductor manufacturing process, to produce a metallic wire lattice.
The oblique deposition process is, however, unsuitable to obtain a conventional rectangular shape having a high aspect ratio (2:1 or 3:1 or more) that is required to obtain the properties required by the WGP, and also unsuitable for large-area processes producing, for example, a TV. In addition, in the oblique deposition process, an asymmetry of a metallic structure with respect to an inclination direction can affect transitive/reflective properties of an incident beam according to an incident orientation. Furthermore, a micro metallic lattice structure is very fragile to external scratches. Also, US 2003/0117708 et al. discloses a more stable structure with respect to external conditions by using a top substrate or by filling an air layer between a metallic lattice and a dielectric.